1. Field of the Invention
The present invention relates to a system for testing liquid crystal and end seal of liquid crystal display cell, and more particularly to a system for testing distributing state of the liquid crystal being injected through a liquid crystal injecting hole and for testing coating state of end seal used for sealing the injecting hole after the liquid crystal is injected.
2. Description of the Related Art
The liquid crystal cell is generally fabricated according to the following steps of; coating a polymeric organic alignment layer between electrodes, i.e. transparent conductors being attached to respectively opposed surfaces of upper and lower glass substrates and rubbing the alignment layer; printing a thermosetting sealing material that a spacer is mixed therein, on the lower glass substrate so as to maintain a selected distance (7.about.10 .mu.m) between the upper and lower glass substrates; attaching the upper glass substrate and the lower glass substrate; and curing the resultant.
There are various techniques for injecting the liquid crystal into the liquid crystal cell, such as those methods of employing yarn made of fiber material, boating and dipping.
According to the method employing yarn, sufficient amount of liquid crystal is absorbed by the yarn made of fiber materials and the yarn is inserted into a boat through a slot provided in the boat. The boat is located adjacent to a liquid crystal injecting hole formed in a liquid crystal cell. And then, the liquid crystal is injected into inner space of the liquid crystal cell according to a vacuum pressure which is preexisted in a liquid crystal injecting chamber and an absorptivity due to the capillary phenomenon.
On the other hand, according to the boating method, the liquid crystal is directly poured into the liquid crystal injecting hole without employing any yarn. According to the dipping method, the liquid crystal is injected by dipping the liquid crystal injecting hole into a tray which is filled with liquid crystal in full.
Accordingly, there are formed two liquid crystal injecting holes at a side of the liquid crystal cell. The liquid crystal is injected through the respective liquid crystal injecting holes, and then the liquid crystal injecting holes are sealed with end seal to prevent from leaking the liquid crystal. Herein, the end seal is generally coated at an outer surface of the liquid crystal injecting hole at a thick of 0.1.about.0.8 mm.
After the liquid crystal injecting hole is sealed with the end seal, uniformity of liquid crystal distribution in the liquid crystal cell is investigated. The reason for investigating the uniformity is because there may be occurred malfunctions when the liquid crystal is not injected uniformly into some portions of the liquid crystal cell. Further, the thickness of end seal must be limited and be uniformed in the range as mentioned above. Only by doing so, leaking of liquid crystal is prevented, and therefore the sealing condition can be investigated.
Conventionally, there are provided an equipment for testing the liquid crystal distribution and another equipment for testing end seal condition, and especially the sealing condition is investigated about the whole liquid crystal cells by means of a microscope.
However, those equipments whose testable range of cell size is limited within 12.1" will be useless since currently the size of liquid crystal cell becomes larger.
Furthermore, since those equipments are separately installed, they require two investigators, which is regarded to as wasting of manpower and there may be occurred scraps in the liquid crystal cells while transferring the liquid crystal cells from one equipment to another equipment.
Since the sealing condition is investigated about the whole liquid crystal cells by means of a microscope, the investigator has eyestrain that results in inaccuracy of the test.